Control system for refrigerating apparatus



y 1943- N. ERLAND AF KLEEN 2,323,901

CONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed Feb. 24, 1941 eShecs-Sheet 1 INVENTOR. JZ/J ZHa/m (1f 11 [196% BY 6) M ATTORNEY y 1943-N. ERLAND AF KLEEN' 2,323,901

CONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed Feb. 24, 1941 6Sheets-Sheet 2 M W n H W .M Km M 8 T M M 2:72 4 W W m m 7 m M w m m M MM m P m {6 Q m 1 5 Fl 5 fly M M B r M o 0 g g M 7 1. r x J 0 w 7 g 00RM. d 050/7 u 5 MkbhtkMQEMk kWfl\Qm 5 July 13, 1943. N. ERLAND AF KLEENCONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed Feb. 24, 1941 6Sheets-Sheet 4 R170 M 5 m W T m g v i m9 3 v I V H July 13, 1943- N.ERLAND AF KLEEN CONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed Feb.24, 1941 6 Sheets-Sheet 5 i INVENTOR. 1722.1 Er/afia If Klee/2 MATTORNEY y 1943- N. ERLAND AF KLEEN I 2,323,901

CONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed Feb. 24, 1941 6Sheets-Sheet 6 Patented July 13, 1943 CONTROL SYSTEM FOR REFRIGERATINGAPPARATUS Nils Erland at Kleen, Stockholm, Sweden Application February24, 1941, Serial No. 380,330

24 Claims.

This invention relates to new and useful improvements in systemsutilizing energy to maintain predetermined conditions in a mass, body,room, space or the like, and is directed more particularly to a controlsystem for regulating the quantity of energy according to the conditionsinside and outside the said mass, body, room, space and the like.

Generally speaking where predetermined conditions are being controlledin a mass, body, space, room and the like, the greater the differencebetween the conditions inside and those outside said mass, the moreenergy has to be supplied thereto. In some systems, the quantity ofenergy supplied to .the energy-producing unit will have to becorrespondingly increased with an increasing difference between theconditions inside and those outside the mass being controlled. Incertain other systems, on the other hand, the quantity of energysupplied to the energy-producing unit will have to be correspondinglydecreased with an increasing difference between the aforementionedconditions.

As an example, where the question is one of refrigeration, among thosesystems falling in the first category can be mentioned, a continuousabsorption system of the water-ammonia-inert gas type, an ordinarycompressor system and the lke, while among those systems coming underthe second category can be found the intermittent dry absorption systemand those systems operating in relatively the same manner. In the lattersystems, the range of operation will be within decreasing limits oftemperature with increasing outside temperature conditions. In otherwords, at a lower temperature outside the mass being controlled, therefrigeration-producing unit can be utilized to a lower end temperaturethan at a higher outside temperature conditions. Consequently, theamount of energy to be supplied to such a refrigeration-producing unitmust be relatively less at a higher outside temperature in order to havethe refrigerating system operate under its most favorable conditions.

Eeretofore, in systems of the types above mentioned, it has not beenpossible to have such systems operate at their best efficiencies duringvarying conditions, that is, when the difierence temperature betweenthat inside the mass and that outside the mass varied, and the greaterthe difference between such temperatures, the

more dif icult it became to maintain the eificiencies of theenergy-producing units.

It is therefore the primary object of the present invention to overcomethe deficiencies in 'systems hereto-fore known, and to this end theinvention consists in a system of control by which it is possible tooperate the energy-producing units at their best efficienciesindependent of the varying conditions not only inside the mass, but alsoof the varying difference between the conditions inside and outside thesame mass. 7

The invention consists also in a control system of this characterresponsive to the conditionsin the mass being controlled as Well as tothe .conditions outside the said mass, for regulating the amount ofenergy supplied to the energy-producing units.

Furthermore, the invention consists in a simple arrangement wherein allof the control members for the regulation of the kind and quantity ofenergy to be supplied, are centralized to form a compact unit with theseparate impulse lines leading therefrom to the different points, suchas inside the mass, outside the mass, and so forth, to be influenced bythe different conditions.

Ihe invention consists further in a unitary control system responsive toa'plurality of separate impulses generated by conditions in differentparts of a mass and the like, and to separate impulses generated byconditions outside said mass.

The new and novel features of the invention will be hereinafter setforth more in detail in the following description, illustrated by way ofexamples in the accompanying drawings, and more particularly pointed outin the appended claims.

Referring to the drawings, in which numerals of like character designatesimilar parts throughout the several views- Fig. 1 is a diagrammaticview of an absorption refrigerating system having a single unit, andillustrating one form of thermostat control system according to theinvention;

Fig. 2 is a detail diagrammatic view with parts broken away and insection, showing a modified form of control system;

Fig. 3 is a temperature chart graphically illustrating the operatingconditions of an absorption refrigerating unit for different room tem-'per'atures;

Fig. 3a is a diagrammatic View of a modified form of thermostat controlsystem for the operating conditions illustrated i Fig, 3;

Fig. 4 is a view similar to Fig. 1, but showing the control systemapplied to absorption refrigerating apparatus having two units operatingin phase, and an adjustable control device;

Fig. 5 is a view similar to Fig. 4 but without the control device andshowing a slightly different arrangement of the control system;

Fig. 6 is a diagrammatic view of a control system for regulating theamount of gas or other fluid medium supplied to a burner for use inheating the boiler absorber of an absorption refrigerating unit;

Fig. 7 is a sectional View taken on line 'I-I of Fig. 6;

Fig. 8 is a sectional view taken on line 88 of Fig. 7;

Fig. 9 is a sectional view taken on line 9-9 of Fig. 6;

Fig. 10 is a vertical section through a modified form of thermostatvalve arrangement for selectively regulating the amount of gas or otherfluid medium supplied to the burner;

Fig. 11 is a view taken along line IIII of Fig. 10;

Fig. 12 is a vertical sectional view through a refrigerator cabinetillustrating diagrammatically a complete absorption refrigerating unitwith a modified form of thermostat control system, responsive to threeseparate reaction impulses namely, evaporator, cabinet and room, forregulating the amount of gas supplied to the burner;

Fig. 13 is an enlarged sectional view of a unitary thermostat controlarrangement generally similar to that illustrated in Fig. 12;

Fig. 13a. is a fragmentary sectional detail of a modified form of one ofthe valves for use in the control system of Fig. 13 for the operatingconditions illustrated in Fig. 3, and

Fig. 14 is a fragmentary sectional view of a modified form of unitarycontrol arrangement of Fig. 13.

In the drawings, referring more particularly to Fig. 1, an absorptionrefrigerating system including a single intermittent unit isdiagrammatically illustrated comprising the usual boiler absorber IE]having an annular compartment containing solid absorption material II,an inner annular cooling jacket I2, and a central vertical flue I3, inwhich is disposed any suitable heating means such for example as anelectrical heating cartridge III to heat the boiler absorber for thegenerating period. From the boiler absorber I0, the gaseous refrigerantpasses upwardly through the conduit I5 into the condenser I6, where itis condensed and flows to an accumulator or collecting vessel I'Ilocated in the upper portion of the refrigerator cabinet I8 andpreferably surrounded by insulating material I9. From the accumulatorII, the liquid refrigerant flows through the evaporator shown in theform of a coil pipe extending into the cabinet I8. During the absorptionperiod, the boiler absorber III is cooled by any suitable means (notshown) and the refrigerant evaporated in the evaporator returns to theboiler absorber to be absorbed by the solid absorbent material I I.

The operation of the unit from one phase to the other is automaticallycontrolled by the usual thermostat switch device comprising a switchlever 2| fulcrumed intermediate its ends as at 22, and operativelyconnected to a transverse rod 23 movable in one direction by a coilspring 24 adjustable by means of threaded nut 25, said transverse rod 23being movable in the opposite direction against the tension of thespring 24 by a bellows diaphragm 26 responsive to a fluid pressuresystem 21 influenced by the temperature of the boiler absorber I0. Oneend of the switch lever 2I carries an electrode 28 connected to asuitable source of electric current and adapted to cooperate on the onehand with a stationary electrode 29 arranged on one side of the switchlever and electrically connected to the heat cartridge Hi, and on theother hand with an abutment 30 disposed on the oppo- Site side of theswitch lever 2| so that upon rocking movement of the switch lever fromone position to the other, the heat cartridge I4 will be intermittentlyenergized and de-energized. A snap spring 3I cooperates with the switchlever 2| to yieldably maintain the latter in either of its extremepositions.

The heat cartridge I4 is adapted to be energized through separatecircuits to produce respectively different amounts of heat, threecircuits being illustrated by way of example in the drawings. Forconvenience, feed line from the source of current has been designated 0and the feed lines of the three separate circuits have been designatedby their voltage I20, I60 and 225 representing minimum or low, medium,and maximum or high heat values, respectively. The minimum, Or low heat,I20, is connected to one end of a mercury switch 32, supported on thelower end of a rocking lever 33 operatively connected to the transversoperating rod 34 of a thermostat arranged in the cabinet I8. The rod 34is movable in one direction by a coil spring 35 adjustable by means ofthreaded nut 36 and is movable in the opposite direction by a bellowsdiaphragm 31 responsive to a fluid pressure system 38 influenced by thetemperature in the cabinet I8. The mercury switch 32 is yieldablymaintained in either of its extreme positions by a snap spring 39 whichcooperates with one end of rocking lever 33.

The opposite end of the mercury switch 32 is electrically connected to amovable electrode 40 carried on the upper end of a rocking switch lever4| fulcrumed intermediate its ends as at 42 and connected at its lowerend to a snap spring 43. The switch lever 4| is operatively connected tothe transverse operating rod 44 of a thermostat responsive to roomtemperature conditions, said rod being movable in one direction by coilspring 45 and in the opposite direction by a bellows diaphragm 41responsive to a fluid pressure system 48 influenced by the temperatureoutside the cabinet IS. The tension of the spring 45 can be regulated bymeans of threaded nut 45 to pre-load the bellows diaphragm for differentoperating conditions.

In one position of the switch lever 4|, the electrode 40 engages acomplementary electrode 49 connected to feed line I of the heatcartridge I4, while in the other position of the switch lever, itselectrod 43 engages a complementary electrode 5 connected to feed line225 of the heat cartridge.

The operation of the control system just described, is believed obvious,it being clear that the cabinet thermostat will operate to regulate theamount of heat supplied to the boiler absorber i0 between apredetermined minimum, through line I29, and a variable maximum, throughline I60 or 225, selectively determined by the room thermostat. In otherwords, as long as the cabinet temperature remains at a predeterminedlevel for which the cabinet thermostat has been adjusted, the mercuryswitch 32 will occupy the position shown in the drawing and th heatcartridge I4 will be energized through line 52% to supply minimum or lowheat to the boiler absorber I0. However, when the cabinet temperaturerises above the predetermined level, the cabinet thermostat will rockthe mercury switch 32 to its opposite position so that the heatcartridge it will be energized either through line I60 to supply amedium amount of heat, or line 225 to supply the maximum amount of heat,dependent upon the position of the switch lever ii in response to theroom thermostat.

In Fig. 2, the mercury switch 32 i shown electrically connected on oneside to a movable electrode on switch lever 4|, While its other side isconnected to the feed line 225. The stationary electrode 59a in thisinstance is connected to the feed line iZil, and electrode a isconnected to the feed line Ital. Thus, in this form of control system,the cabinet thermostat operates to regulate the amount of heat suppliedto the boiler absorber between a variable minimum, either through lineI20 or line IEO, selectively determined by the room thermostat, and apredetermined maximum through line 225.

Referring to Fig. 3, the temperature conditions in the boiler absorberof an air-cooled absorption refrigerating unit of the intermittent typeare graphically illustrated, Where it is de sired to maintainpredetermined temperature conditions in the evaporator substantially constant for three different temperature conditions outside a refrigeratorcabinet. In view of the fact that in a refrigerating system of this typethe boiler absorber cannot be cooled down during each absorption periodto below a few degrees above the room temperature, and that the upperlimit of the boiler temperature range is fixed, it

follows that with an increasing room temperature a correspondinglydecreasing amount of heat is required for each generating period. Forexample, for a room temperature up to 70 F., the rise in temperature inthe boiler absorber for each generating period will follow the heavyline 5! in Fig. 3 and the corresponding temperature drop in the boilerduring each absorption period will follow lighter line 52. For a roomtemperature from 70 F. to 90 F., the temperature rise and thecorresponding temperature drop in the boiler will follow heavy line 53and lighter line 5 3, respectively, while for the room temperature from90 F. to 110 F., the temperature rise and corresponding temperature dropwill follow heavy line 5-5 and lighter line 56, respectively. For thethree temperature ranges mentioned, the temperature in the evaporatorwill follow heavy line 5? during each generating or heating period, andl ghter line 58 during each absorption period.

It will thus be observed that for a room temperature up to 70 F., moreheat is required for the boiler absorber than for either of the othertwo ranges of room temperature, and that for a room temperature from 90F. to 110 F., less heat is required for the boiler than for a roomtemperature from 70 F. to 90 F.

For this type of operation, an arrangement similar to that shown in Fig.3a can be used wherein the heat cartridge M has four feed lines, E00,301i, 350 and 500, respectively. One side of the mercury switch 32 isconnected to feed line I Gil, while its opposite side is electricallyconnected to the electrode dim of the room thermostat switch lever Ma.The electrode 40a in this arrangement is adapted to cooperate with threeseparate stationary electrodes L, M and H connected to feed lines 300,350 and 300, respectively. It will thus be observed that with thiscontrol system, the cabinet thermostat operates to regulate the supplyof heat to the refrigerating I-Hi system from a predetermined low (50)to a variable high, either minimum high (300), medium high (350), ormaximum high (505), dependent on the room temperature outside therefrigerator cabinet. In other words for a room temperature up to 70 F.for example, the cabinet thermostat will operate to energize the heatcartridge M either through feed line I00, or feed line 400; for a roomtemperature from 70 F. to F., the heat cartridge will be energizedeither through feed line 30 or feed line 350, and with a roomtemperature from 90 F. to F., the heau cartridge will be energizedeither through feed line I00 or feed line 35w.

Referring to Fig. 4, the control system previously described is shownapplied to an absorption refrigerating system having two intermittentlyand alternately operating units generally indicated as A and B,respectively, each similar to the unit heretofore described inconnection with Fig. 1. For convenience, the various parts of unit Ahave been designated by the same reference characters used in Fig. 1while the corresponding parts of unit B have been distinguished by theprime of the numeral.

The operation of the units A and B from one phase to the other isautomatically controlled by a thermostat switch similar to that shown inFig. 1 with the exception that the transverse rod 23 operativelyconnected to the switch lever 2! is movable in opposite directions byoppositely disposed bellows diaphragms 26 and 23, the former responsiveto the fluid pressure system 27 influenced by the temperature of boilerabsorber i0 and the latter r sponsive to a fluid pressure system 21influenced by the temperature of the boiler absorber 10'.

In this installation, the switch lever 21 carries a plurality ofelectrodes 59, 50, 6t and 62 adapted to cooperate in one position of theswitch lever 21 with a similar number of complementary electrodes 63,64, S5 and 56, respectively, arranged on one side of the switch leverand, in the other position of the switch lever, electrodes 59, 50, 8Fand 62 cooperate with a like number of complementary electrodes 63, 6d,65" and 66, respectively, arranged on the opposite side of the switchlever. The switch lever electrode 59 is electrically connected to asource of current, for example, the negative or minus line, while thestationary electrodes 63 and 63' are connected to the 0 feed lines ofthe heat cartridges I4 and I4, respectively. One side of the mercuryswitch 32 controlled by the cabinet thermostat is electrically connectedto the switch lever electrode 82, while the other side of the mercuryswitch is similarly connected to the switch lever electrode 40 of theroom thermostat. The stationary electrodes 49 and 50 of the roomthermostat are electrically connected to the switch lever electrodes 6]and 60, respectively.

The refrigerating system illustrated in Fig. 4 also includes a controldevice generally similar to that shown and described in my copendingapplication Serial No. 369,780, filed December 12, 1940, coveringControl mechanism for refrigerating apparatus. The control device isgenerally indicated as 6'! and has an arm 58 rotatable about a centralaxis 69 and adjustable from a position marked Off when the refrigeratingsystem is not in operation, to three separate operating positions markedI, II and III, respectively, for different conditions of operation ofthe refrigerating system.

For position I, the control device 67 is provided on its upper face withtwo diametrically opposed pairs of contacts Ill and IS, the formeradapted to be engaged by a circuit-closing brush H arranged on theunderside of one end of the arm 68, and the latter by a similar brushII' on the opposite end of the arm 68. One of the contacts III isconnected to the stationary electrode 66 and the other is connected tothe line I20 of heat cartridge I l, while one of contacts III isconnected to the stationary electrode 66' and the other is connected toline I20 of heat cartridge For this position of the control device, thecabinet thermostat and the room thermostat will be inoperative toregulate the amount of heat supplied for the reason that the heatcartridges I4 and I4 will be intermittently and alternately energizedonly through the minimum line I20. Consequently, the units A and B willoperate to produce only sufficient cold to maintain a cool temperaturein the cabinet I8 but not necessarily sufiicient to freeze water.

For position II on the control device which position represents thenormal operating conditions of the refrigerating system, the controldevice has three separate pairs of contacts I2, I3 and I4 on its upperface adapted to be engaged by circuit-making brushes II, 75 and I6,respectively, on one end of the arm 68. Diametrically opposite the abovementioned three pairs of contacts, the control device 61 has three morepairs of contacts I2, I3 and I4 adapted to be engaged by brushes Il, I5and I6, respectively, on the other end of the arm 68. One of the contact12 is connected to the line I of the heat cartridge Id and the other ofsaid contacts is connected to the stationary electrode 66. One of thecontacts I3 is connected to feed line ISiE of heat cartridge I l and theother is connected to electrode 65. One of contacts I6 is connected tofeed line 225 of the heat cartridge I l and the other is connected toelectrode M. The contacts I2, I3 and I4 are similarly connected to thecorresponding feed lines I28, I and 225 of heat cartridge I I and thecorresponding electrodes 66', and 64.

Thus, with the arm 68 occupying position I on the control device 67, theheat cartridges I4 and Id can be energized through three differentcircuits to supply correspondingly difierent amounts of heat to theboiler absorbers I0 and II), respectively, and the control systemillustrated will operate as follows: The cabinet thermostat willregulate the amount of heat from a predetermined minimum to a variablemaxil mum, either medium or high, selectively determined by the roomthermostat. In other words, with the mercury switch 32 occupying theposition shown, the heat cartridges I4 and It will be intermittently andalternately energized through their corresponding feed lines I20. As thetemperature rises in the cabinet I8 sufficiently to permit bellowsdiaphragm 3! to rock mercury switch 32 to its opposite position, theheat cartridges will then be energized through their feed lines I60 fora predetermined room temperature when electrode 48 of switch lever 4|contacts electrode 59, or the heat cartridges will be energized throughtheir feed lines 225 if the room temperature rises sufiiciently to rockswitch lever 4| to the position when electrode ll) contacts electrode50.

In order to increase the efliciency of condensers I6 and I6 when themaximum heat is supplied to the corresponding bolier absorbers IE! and IO, I have shown a motor-driven fan assembly 'II disposed in the lowerportion of a flue F in which is arranged the condensers I6 and IS. Themotor of the fan assembly is electrically connected to the negative lineof the current source and to the electrode 50 so that whenever the heatcartridges I l and I I are energized through feed lines 225, the motorof the fan assembly II will also be energized to operate the fan.

For position III on the control device SI, a pair of contacts I areadapted to be engaged by brush II on the arm 68 and, diametricallyopposite to contacts I, two separate pairs of contacts I and I" areprovided on the control device 6? adapted to be engaged by the brushesI5 and I6, respectively, on the arm 68. One of the contacts I isconnected to the feed line 225 of cartridge I4 and the other isconnected to electrode 8 1, while contacts I are similarly connected tofeed line 225 of cartridge I4 and electrode 64 respectively. One of thecontacts I is connected to the fan assembly I? while the other isconnected to the positive line of the current source.

It will thus be seen that with the arm 63 occupying position III on thecontrol device Bl, the heat cartridges I 4 and I4 will be intermittentlyand alternately energized only through feed lines 225 to supply maximumheat to the respective boiler absorbers I0 and I8 and the motor of thefan assembly I! will be continuously energized, the cabinet and roomthermostats being inoperative to regulate the amount of heat supplied.For this position of the control device 62 the cycles of the units A andB will naturally be shorter than for either of the first two positionsof the control device with the result that quicker freezing conditionsand consequently lower temperatures will be produced in the cabinet I8.

The absorption refrigerating system illustrated in Fig. 5 is the same asthat just described in connection with Fig. 4 with the exception that nocontrol device is used for adjusting the operation of the refrigeratingsystem for difierent conclitions. Furthermore, a slightly differentarrangement of control system is shown. Instead of increasing the amountof heat supplied to the boiler absorbers from minimum or low, to maximumor high, with a rise in room temperature, the control system of Fig. 5will decrease the amount of heat relatively with rising roomtemperature. As shown in the drawing, one side of the mercury switch 32is connected to electrode 62 of switch lever 2| and its opposite side isconnected to electrode ll! of switch lever M. However, instead of beingconnected to electrode SI of switch lever 2! as shown in Fig. 4, theelectrode 59a is connected to electrode 59 cooperating with theelectrodes 64 and 64' controlling maximum feed lines 225, whileelectrode 50a is connected to electrode 6|.

The operation of the foregoing system is believed obvious withoutfurther description.

In Fig. 6, the control system is applied to a gas installation forregulating the amount of gas supplied to a gas burner I8 employed as thesource of heat for the refrigerating apparatus instead of the electricalheating system here ofore described. The gas flows from a suitablesource indicated in the drawings as Main gas line through three branchconduits I9, and 8 I, each provided with a valve for regulating theamount of gas passing therethrough; for example, a predetermined minimumamount through each of conduits I9 and 80 and a predetermined maximumamount through conduit BI. The conduit I9 terminates in communicationwith a valve chamber 82 in which is arranged a valve 83' carried on oneend of the pivoted switch lever 33a of the cabinet thermostat forcontrolling the admission of gas into said chamber from either conduit'19 or from a branch conduit 84 leading from conduit 8| and connectedinto the valve chamber 82 adjacent conduit I9. A valve 85, carried onone end of the pivoted switch lever Ma oi the room thermostat, isinterposed in the branch conduit 84 and is provided with a segmentalopening 86 for varying the cross-sectional area of the conduit passage,whereby variable amounts of gas can flow through the conduit 84,-depending upon the room temperature. From the valve chamber 82, the gasflows through conduit 81.

Each of the conduits 30, 8! and 81 terminates in communication with amaster control valve generally indicated as 88 which is adjustable froma position marked Oil to positions I, II, III for controlling theoperation of the refrigerating system for diiferent operating conditions, similar to the control device 6'! heretofore described inconnection with Fig. 4. As clearly shown in Figs. '7 and 8, the mastercontrol valve consists of a casing 89 into which the conduits 80, 8! and8| are connected corresponding to positions I, II, and III,respectively, indicated on the upper face of the casing. A valve member90 rotatably mounted in the casing is drilled longitudinally from oneend to provide a central bore 9| which terminates at its inner end incommunication with a transverse radial inlet opening 92 provided in anenlarged portion of the valve member and adapted to register with anyone of the openings formed by the conduit connections 80, 8| and 81,upon rotation of the valve, to form an inlet passage for the gas. Theouter end of the bore 9| is closed by any suitable means such as athreaded plug 93. The opposite end of the valve mcmber 90 terminates ina reduced stern portion a which projects through the upper face of thecasing 89 and carries a transverse arm or pointer 94 to indicate thedifl'erent positions of thevalve member 90.

A second transverse radial opening 95 is provided in a reduced portionof the valve member 90 for the passage of the gas from the central bore9| into a gas chamber 96 in the casing 89 from which the gas flowsthrough outlet conduit 91 connected into the casing 89 corresponding tothe 01f position of the master control valve 88. '1

A radially projecting lug 98 carried on the reduced portion of the valvemember 90 in the plane of the outlet conduit connection 91 is adapted toclose the opening in said outlet connection when the valve member 90 isrotated to the Off position and to open the same when the valve memberis rotated to positions I, II or III.

With the valve member 90 adjusted to position I, its radial opening 92will register with conduit connection 80 so that only a predeterminedminimum amount of gas will flow from the Main gas line to the outletconduit 91. However, with the valve member 90 rotated to position II,its opening 92 will register with branch conduit connection 8! and thegas will flow either through conduit I9 from the Main gas line, orbranch conduit 84, depending upon the cabinet temperature. In otherwords, if the predetermined temperature for which the cabinet thermostathas been adjusted exists in the cabinet or region being cooled, thevalve 83 will occupy the position shown in Fig. 6 and a predeterminedminimum amount of gas will flow through conduits I9, 81 and 91 to theburner 18.

When the aforesaid temperature changes, the cabinet thermostat will thenmove valve 83 across conduit I9 to close the latter and open branchconduit 84, thereby permitting more gas to flow to the burner I8, theamount of which is regulated by the valve 85 controlled by th roomthermostat in accordance with the room temperature.

With the valve member adjusted to position III, its radial opening 92will register with conduit connection SI and only a predeterminedmaximum amount of gas will flow to the burner 18,

the thermostat valves 83 and 85 being inoperative in this position ofthe valve member to regulate the amount of gas supplied.

, Referring to Fig. 10, another form of gas installation is shownincluding a housing 99 divided centrally by a transverse partition I00to provide two separate gas chambers IN and I02 into which the gasenters through branch conduits I03 and I 04, respectively, from a maingas line I05. A third branch conduit I06 from the main gas line I05 isconnected to the inlet end of a central bore I01 extendinglongitudinally through the partition I 00 and terminating at its outletend in communication with an outlet conduit I08 leading to a gas burner(not shown). Preferably, each of the branch conduits I03, I05 and I06 isprovided with a valve I 0311, I04a and W541, respectively, to regulatethe amount of gas flowing therethrough, for example, a predeterminedminimum amount through branch conduit I03 and a predetermined maximumamount through branch conduit I04, while only a sufficient amount of gasis permitted to flow through branch conduit I06 to maintain a pilotflame in the burner.

The partition I00 is provided with a transverse opening I09 extendingfrom one gas chamber to theother for the passage of gas from chamber I02to chamber II. A second transverse opening I I0 in the partition I00extends from chamber IOI to the central bore I0'I for the passage of gasto the burner. The amount of gas entering central bore I0'I from thechamber IOI is regulated within a predetermined range by any suitablevalve III operated by the cabinet thermostat, the valve shown in thedrawings being in the form of a circular plate rotatable in the chamber.I 0I about a central axis I I2 projecting outwardly from one side ofthe partition I00. The valve plate I I I has a cut out segmental slot II3 adapted to cooperate with the opening II 0 for varying thecross-sectional area of the gas passage to permit the flow of differentamounts of gas into the central bore I01 for delivery to the burner. Thevalve plate III is rotated in response to the temperature in the cabinetor region being cooled, by means of an arm I I4 eccentrically mounted onone side of the plate and connected to the reciprocatable rod 34a of thebellows diaphragm 31a responsive to a fluid pressure system 38apartially shown but leading to the cabinet or region being cooled.

The amount of gas supplied from chamber I 02 to chamber IOI is regulatedby a valve plate I I5 similar to valve plate I I I but rotatable in thegas chamber I02 about a central axis H5 in response to the temperatureoutside the cabinet. Valve .plate I I 5 is provided with a segmental cutout slot II"! which cooperates with the opening I09 to vary thecross-sectional area of the gas passage, whereby different amounts ofgas can pass from chamber I52 into chamber IBI. The valve plate H isrotated about its axis IIS by means of an arm I I8 eccentrically mountedon one side of the valve plate and operatively connected to thereciprocatable rod 44a of the bellows diaphragm 7a responsive to a fluidpressure system 48a influenced by the temperature outside the cabinet.In operation, gas will flow continuously to the gas chambers IOI and I02through the respective branch conduits I03 and I04. The cabinetthermostat will control the valve plate III to permit the flow of gasfrom the chamber IOI to the burner between a predetermined minimum and avariable maximum, determined by the room thermostat controlling thevalve plate I I5.

Referring to Fig. 13, a further embodiment of the invention isillustrated wherein all of the thermostat valves required to control thesupply of heat and to regulate the amount of heat supplied to arefrigerating system are arranged in a common housing or casing I toprovide a unitary thermostat control device.

I 22 into an inlet chamber I23, an intermediate chamber I24 and anoutlet chamber I25. A horizontal partition I26 divides the intermediatechamber I24 into an upper compartment and a lower compartment. Gas issupplied to the inlet chamber I23 through conduit I21 leading from asuitable source (not shown). The partition I22 is provided with atransverse opening I28, the size of which can be adjusted by threadedplug I29 for the passage of a predetermined amount of gas from the inletchamber I23 to the intermediate chamber I24.

From the intermediate chamber I24 to the outlet chamber I25, the passageof gas is controlled by a valve I30 cooperating with a valve seat formedby a transverse opening in the partition I2I. Valve I30 is actuated by abellows diaphragm I3I arranged in one side of the housing I20 andresponsive to a fluid pressure system I32 partially shown but leading tothe cabinet and influenced by the temperature therein. A similar valveI33 operable by a bellows diaphragm I34 arranged in the opposite side ofthe housing I20 and responsive to a fluid pressure system I35,cooperates with a valve seat forming an opening in the partition I22 toregulate the amount of gas supplied to the upper compartment of theintermediate chamber I24 according to temperature conditions outside thecabinet. valve I35, operatively connected to a bellows dia-- phragm I31adjacent bellows I34 but responsive to fluid pressure system I38influenced by the evaporator temperature of the refrigerating system,cooperates with a valve seat formed by another transverse opening in thepartition I22 to regulate the amount of gas supplied to the lowercompartment of the intermediate chamber I24. A transverse opening I39 inthe partition I23 establishes communication between the lowercompartment of the intermediate chamber I24 and the outlet chamber I25from which outlet chamber the gas flows through conduit I40 to a burner(not shown).

The flow of gas through the outlet conduit I40 to the burner isautomatically controlled by the usual thermostat switch device shown inthe form of a valve I4I slidably supported on one end of a pivoted armI42 in the outlet chamber I25. The valve I4! is actuated by a rod I43operatively con- The housing I20 is divided by means of verticalpartitions I2! and A third nected to the pivoted arm I42 and movable ina direction to open the valve by means of a coil spring I44, said rodbeing movable in a direction to close the valve by a bellows diaphragmI45 responsive to a fluid pressure system I46 influenced by thetemperature in the boiler absorber (not shown). A snap spring I41cooperates with the free end of the pivoted arm I42 to yieldablymaintain the valve MI in either its fully closed or fully openpositions.

In order to maintain a pilot flame for the burner, a by-pass conduit I48is provided leading from the upper compartment of the intermediatechamber I24 to the outlet conduit I40 and, if desired, a threaded plugvalve I49 may be interposed in the by-pass conduit to regulate theamount of gas flowing through the latter, thereby adjusting the pilotflame.

In Fig. 12, a refrigerator cabinet I8 is illustrated equipped with asingle absorption refrigerating unit similar to that shown in Fig. l butincluding a gas burner I8 as the heating means for the boiler absorberfor the generating phase operation, and a secondary cooling system forthe circulation of a cooling medium through the boiler absorber jacketI2, for the absorption phase operation of the unit to cool the boilerabsorber.

The supply of gas and the amount of gas supplied to the burner I8 arecontrolled by a unitary thermostat control device similar to that shownin detail in Fig. 13 with the exception that, for purposes ofillustration, the gas outlet chamber is arranged in the gas compartmentof a combined liquid and gas valve chamber I50 separate from the housingI20a and the bellows diaphragm I45a responsive to the fluid pressuresystem I46a in thermal contact with the boiler absorber I0, operates apair of valves I5I and I52, the former arranged in the gas compartmentof the valve chamber I50 to control the supply of gas to the burner 10,and the latter arranged in the liquid compartment of the valve chamberto control the circulation of the cooling medium through the secondarysystem. Valves I5I and I52 are oppositely disposed so that when one isclosed, the other is open.

The cooling medium enters the bottom of the jacket I2 through a conduitI 53 leading from the liquid compartment of the valve chamber I50 andpasses upwardly through outlet conduit I54 leading to a secondarycondenser I55 arranged below the primary condenser I6. From thecondenser I55, the cooling medium flows through conduit I56 to acollecting vessel I57 and is delivered to the liquid compartment in thevalve chamber I50 through conduit I58. In order to increase theefliciency of the air-cooled condensers I6 and I55, a baffle plate I59is interposed between said condensers to divide the air into separatestreams passing around the respective condensers.

The operation of the refrigerating unit just described is as follows:

The bellows diaphragm I45a will automatically control the operation ofthe unit from one phase to the other. For the absorption phase, thevalve I5I will be closed to shut off the supply of gas to the burner 18,and the valve I52 will be opened to permit circulation of the secondarycooling medium through the boiler absorber jacket I2. For the generatingphase, the valve I52 will be closed and the valve I5I opened. The fluidpressure system I32 of the cabinet thermostat will actuate valve I30 toregulate the flow of gas from a predetermined minimum to a variablemaximum, determined by the room temperature which will actuate valve I33through the fluid pressure system I35 of the room thermostat to increasethe amount of gas supplied with an increasing room temperature. Thethird valve I36 actuated by the fluid pressure system I38 of theevaporator thermostat will be opened whenever the temperature adjacentthe evaporator increases, such for example when Water is placed in theice-tray of the ice-tray compartment 260 in the cabinet I8.

For the operation of a refrigerating system requiring less heat with anincreasing room temperature, such as shown in Fig. 3, a double valvearrangement illustrated in Fig. 13a may be employed in place of thevalve I33 of Fig. 13. The double valve has a valve head I33a cooperatingwith a valve seat on one side of the partition I22 and an oppositelydisposed valve head I331) spaced longitudinally from the valve head I33aand cooperating with a valve seat in the other side of the partition.

For a refrigerating system employing two intermittently operating units,the unitary thermostat control device of Fig. 13 can be modified alongthe lines suggested in Fig. 14, wherein the gas outlet chamber Iaaccommodates a pair of alternately operating valves MI and I4I, theformer controlling the flow of gas through outlet conduit I48 to theburner I3 in the flue I3 of one of the units, and the latter controllingthe flow of gas through a second outlet conduit I40 leading to anotherburner I8 in the flue I3 of the other unit. Valve I4! is actuated by theoperating rod I43 of the bellows diaphragm I45 responsive to the fluidpressure system I48 in thermal contact with the boiler absorber ofoneunit, while valve MI is actuated by operating rod I43 of a secondbellows diaphragm I45 responsive to a fluid pressure system I46 inthermal contact with the boiler absorber of the other unit. Valves MIand III are operatively connected to the opposite ends of a fulcrumedlever I42; cooperating with a snap spring I Ila to yieldably maintainsaid valves in either of their extreme positions. The by-pass conduitI48 in this form of the control device terminates in diverging pilotjets I and I68 adjacent the burners I8 and I8, re spectively,

It will thus be seen from the foregoing description that I have provideda control system which will automatically increase the quantity ofenergy supplied to that type of energy-producing unit requiring suchincreased amount with an increasing difference between the temperatureinside and that outside the mass, body, space, cabinet and the like;that the control system herein disclosed can also be used to supply arelatively decreasing amount of energy to that type of energyproducingunit requiring the same with an increasing temperature difference, andthat the control system, while responsive to diiferent conditions at aplurality of points, is centralized into a compact unitary arrangementfrom which the impulse lines lead to said plurality of points.

While I have shown several embodiments of my control system applied torefrigerating systems of the direct expansion type, it is to beunderstood that the invention is not to be confined in this respect, asobviously the control System can also be applied in connection withrefrigerating systems of the accumulative type using a storage tankhaving a eutectic mixture or a brine, or to refrigeratingsystemsembodying a combination of the direct expansion and accumulativeprinciples. Moreover, the invention is not to be limited in its use torefrigeration, but can be employed in connection with any systemutilizing energy, such as direct and indirect heating systems, airconditioning systems, heat exchange systems, and the like, where it isdesired to regulate the operation of such energy utilizing systems fordifferent operating conditions.

From the foregoing it is believed that the construction, operation andadvantages of the control system herein disclosed may be readilyunderstood by those skilled in the art without further description, itbeing borne in mind that numerous changes may be made without departingfrom the spirit of the invention as set out in the following claims.

What I claim is:

1. In an absorption system of refrigeration operating to cool anenclosed space or the like to maintain a predetermined condition thereinand including means for supplying heat to said system for the operationthereof; a unitary thermostat device including means responsive to thetemperature in the space being cooled for regulating the supply of heatbetween a predetermined value and a variable value, and means responsiveto the temperature outside the space being cooled for determining thevalue of said variant.

2. The combination with an absorption system of refrigeration operatingto cool an enclosed space or the like to maintain predeterminedconditions therein, a part of said system adapted to be supplied withheat from an outside source for the operation of said system, andanother part of said system being arranged to produce refrigeration insaid enclosed space; of thermostat means responsive to the temperaturein the first named part of said system for controlling thesupply of heatthereto, separate thermostat means responsive to the temperature in thesecond named part of said system for regulating the amount of energysupplied to said first named part, and a plurality of thermostat meansseparately responsive to the temperature inside and outside said spacefor regulating the amount of energy supplied to said first named part inaccordance with the demands inside the space being cooled relative tothe ambient temperature.

3. In absorption refrigerating apparatus operating to cool an enclosedspace and the like and including refrigerant generating means adapted tobe heated; the combination with heating means for said generating means;of means responsive to the temperature in the space being cooled forregulating the heat between a fixed value and a variable value, andseparate means responsive to the temperature outside the space beingcooled determining the value of said variant.

4. In absorption refrigerating apparatus operating to cool an enclosedspace and the like and including refrigerant generating means adapted tobe heated; the combination with heating means for said generating means;of means responsive to the temperature in the space being cooled forregulating the heat between a predetermined minimum and a variablemaximum, and separate means responsive to the temperature outside thespace being cooled determining the value of said variable maximum.

5. In absorption refrigerating apparatus operating to cool an enclosedspace and the like and including refrigerant generating means adapted tobe heated; the combination with heating means for said generating means;of means responsive to the temperature in the space being cooled forregulating the heat between a predetermined minimum and a variablemaximum, and separate means responsive to the temperature outside thespace being cooled determining the value of said variable maximum, thevalue of said variable maximum determined by said last named varyingdirectly in accordance with the ambient temperature variations.

6. In absorption refrigerating apparatus oper ating to cool an enclosedspace and the like and including refrigerant generating means adapted tobe heated; the combination with heating means for said generating means;of means responsive to the temperature in the space being cooled forregulating the heat between a predetermined minimum and a variablemaximum, and separate means responsive to the temperature outside thespace being cooled determining the value of said variable maximum, thevalue of said variable maximum determined by said last named meansvarying inversely with respect to the ambient temperature variations.

'7. In absorption refrigerating apparatus operating to cool an enclosedspace and the like and including refrigerant generating means adapted tobe heated; the combination with heating means for said generating means;of means responsive to the temperature in the space being cooled forregulating the heat between a predetermined maximum and a variableminimum, and separate means responsive to the temperature outside thespace being cooled determining the value of said variable minimum.

8. In absorption refrigerating apparatus operating to cool an enclosedspace and the like and including refrigerant generating means adapted tobe heated; the combination with heating means for said generating means;of means responsive to the temperature in the space being cooled forregulating the heat between a predetermined maximum and a variableminimum, and separate means responsive to the temperature outside thespace being cooled determining the value of said variable minimum, thevalue of said variable minimum determined by said last named meansvarying directly in accordance with the ambient temperature variations.

9. In refrigerating apparatus of the intermittent absorption typeoperating to cool an enclosed space and including combined generatingand absorbing means adapted to be heated intermittently, the combinationwith heating means for said combined generating and absorbing means, andmechanism controlling the operation of said heating means to heat saidcombined generating and absorbing means intermittently; of meansresponsive to the temperature in the space being cooled for regulatingthe heat supplied by said heating means between a fixed value and avariant, and separate means responsive to the temperature outside thespace being cooled for determining the value of said variant.

10. In refrigerating apparatus of the intermittent absorption typeoperating to cool an enclosed space and including combined generatingand absorbing means adapted to be heated intermittently, the combinationwith heating means for said combined generating and absorbing means, andmechanism controlling the operation of said heating means to heat saidcombined generating and absorbing means intermittently; of meansresponsive to the temperature in the space being cooled for regulatingthe heat supplied by said heating means between a predetermined Lilminimum and a variable maximum, and separate means responsive to thetemperature outside the space being cooled determining the value of saidvariant.

11. In refrigerating apparatus of the intermittent absorption typeoperating to cool an enclosed space and including combined generatingand absorbing means adapted to be heated intermittently, combinationwith heating means for said combined generating and absorbing means, andmeans controlling the operation of said heating means to heat saidcombined generating and absorbing means intermittently; of meansresponsive to the temperature in the space being cooled for regulatingthe heat supplied by said heating means between a predetermined minimumand a variable maximum, and separate means responsive to the temperatureoutside the space being cooled determining the value of said variant,the value of said variable maximum determined by said last named meansvarying inversely with respect to the ambient temperature variations.

12. In refrigerating apparatus of the intermittent absorption typeoperating to cool an enclosed space and including combined generatingand absorbing means adapted to be heated intermittently; the combinationwith heating means for said combined generating and absorbing means, andmeans controlling the operation of said heating means to heat saidcombined generating and absorbing means intermittently; of meansresponsive to the temperature in the space being cooled for regulatingthe heat supplied by said heating means between a predetermined maximumand a variable minimum, and separate means responsive to the temperatureoutside the space being cooled determining the value of said variant.

13. In refrigerating apparatus of the intermittent absorption typeoperating to cool an enclosed space and including combined generatingand absorbing means adapted to be heated intermittently, the combinationwith heating means for said combined generating and absorbing means, andmeans for controlling the operation of said heating means to heat saidcombined generating and absorbing means intermittently; of meansresponsive to the temperature in the space being cooled for regulatingthe heat supplied by said heating means between a predetermined maximumand a variable minimum, and separate means responsive to the temperatureoutside the space being cooled determining the value of said variant,the value of said variable minimum determined by said last named meansvarying directly in accordance with ambient temperature variations.

14. In refrigerating apparatus of the intermittent absorption typeincluding at least two units operating in phase relation to each Otherfor the production of substantially continuous refrigeration to cool anenclosed space, each unit having a boiler-absorber; the combination withheating means for said boiler-absorbers, and thermostat mechanismresponsive to the temperature in each of said boiler-absorbers forselectively controlling the supply of heat to said boiler-absorbers; ofthermostat means responsive to the temperature in the space being cooledfor regulating the supply of heat to said boilerabsorbers between afixed value and a variant, and separate thermostat means responsive tothe temperature outside the space being cooled for determining the valueof said variant.

15. In refrigerating apparatus of the intermittent absorption typeincluding at least two units operating in phase relation to each other.for the production of substantially continuous refrigeration to cool anenclosed space, each unit having a boiler-absorber; the combination withheating means for said boiler-absorbers, and thermostat mechanismresponsive to the temperature in each of said boiler-absorbers forselectively controlling the supply of heat to said holler-absorbers; ofthermostat means responsive to the temperature in the space being cooledfor regulating the supply of heat to said boilerabsorbers between apredetermined minimum and a variable maximum, and separate thermostatmeans responsive to the temperature outside the space beingcooleddetermining the value of said variant inversely with respect to ambienttemperature variations. V

16. In refrigerating apparatus of the intermittent absorption typeincluding at least two unitsoperating in phase relation to each otherfor the production of substantially continuous refrigeration to cool anenclosed space, each unit having a boiler-absorber; the combination ofheating means for said boiler-absorbers, thermostat control mechanismresponsive to the temperature in each of said boiler-absorbers forselectively controlling the supply of heat to said boiler-absorbers, anadjustable control device movable to different positions for adjustingthe amount of heat supplied to said boiler-absorbers for differentoperation conditions of the units, at least one position of said controldevice permitting the supply of variable amounts of heat to saidboiler-absorbers, thermostat means responsive to the temperature in thespace being cooled and operative at said one position of the controldevice for regulating the supply of heat to said boiler-absorbersbetween a predetermined minimum and a variable maximum, and separatethermostat means responsive to the temperature outside the space beingcooled for determining the value of said variant.

17. In absorption refrigerating apparatus operating to cool an enclosedspace and including a refrigerant evaporating unit arranged in the spaceto be cooled and refrigerant generating means arranged outside the saidspace; the combination of heating means for said generating means,thermostat means responsive to the temperature in the space being cooledfor regulating the supply of heat between a fixed value and a variablevalue, separate thermostat means responsive to the temperature outsidethe space being cooled for determining the value of said variant, andmeans responsive to the temperature of said refrigerant evaporating unitfor regulating the supply of heat independently of said first-named andsecond-named thermostat means.

18. In absorption refrigerating apparatus operating to cool an enclosedspace and including refrigerant generating means and fuel burner meansfor heating the same; the combination with fuel supply means for saidburner means; of thermostat valve means responsive to the temperature inthe space being cooled for regulating the supply of fuel between a fixedvalue and a variable value, and separate thermostat means responsive tothe temperature outside the space being cooled for determining the valueof said variant.

19. In absorption refrigerating apparatus operating to cool an enclosedspace and including refrigerant generating means and fuel burner meansfor heating said refrigerant generating means; a unitary thermostatcontrol including a valve responsive to the temperature in the spacebeing cooled for regulating between a fixed value anda variant thesupply of fuelto said burner means in accordance with temperaturevariations in the space being cooled, and a second valve responsive tothe temperature outside the space being cooled for determining the valueof said variant in accordance with the ambient temperature. 7 i

20. In refrigerating apparatus of the intermittentabsorption typeoperating to cool an enclosed space and including refrigerant generatingmeans and fuelburner means for heating said refrigerant generatingmeans; a unitary thermostat control including a valve responsive to thetemperature in the space being cooled for regulating between apredetermined minimum and a variable maximumthe supply of fuel inaccordance with temperature variations in the said space, a second valveresponsive to the temperature outside the space beingcooled fordetermining the. amount of saidvariable maximum in accordance with theambient temperature, the amount determined by said second valve varyinginversely with respect to variations in the ambient temperature, andvalve means responsive to the temperature in said refrigerant generatingmeans for controlling the so-regulated supply of fuel to said burnermeans. a

21. In refrigerating apparatus of the intermittent absorption typeincluding at least two units operating in phase relation to each otherfor the production of substantially continuous refrigeration to cool anenclosed space, each unit having a boiler-absorber and a fuel burnertherefor; a unitary thermostat control including a valve responsive tothe temperature in the space being cooled for increasing and decreasingthe supply of fuel in accordance with temperature variations in thespace being cooled, a second valve responsive to the temperature outsidethe space being cooled for varying the maximum amount of fuel regulatedby said firstnamed valve in accordance with variations in the ambienttemperature, and valve means responsive to the temperature in each ofsaid boilerabsorbers for selectively controlling the soregulated supplyof fuel to said fuel burners.

22. In absorption refrigerating apparatus operating to cool an enclosedspace and including refrigerant generating means, fuel burner means forheating said generating means, and refrigerant evaporating means; aunitary thermostat control including a valve responsive to thetemperature in the space being cooled for increasing and decreasing thesupply of fuel in accordance with temperature variation in said space, asecond valve responsive to the temperature outside the space beingcooled for varying the maximum amount of fuel regulated by said firstnamed valve in accordance with variations in the ambient temperature,and a third valve responsive to the temperature of said refrigerantevaporating means for increasing and decreasing the supply of fuel tosaid burner means in accordance with temperature variations in saidrefrigerant evaporating means independently of the temperature in thespace being cooled and of the ambient temperature.

23. In refrigerating apparatus of the intermittent absorption typeoperating to cool an enclosed space and including refrigerant generatingmeans, fuel burner means for heating said generating means, andrefrigerant evaporating means; a unitary thermostat control including avalve responsive to the temperature in the space being cooled forincreasing and decreasing the supply of fuel in accordance withtemperature variations in said space, a second valve responsive to thetemperature outside the said space for varying the maximum amount offuel regulated by said first named valve in accordance with variationsin the ambient temperature, a third valve responsive to the temperatureof said refrigerant evaporating means for increasing and decreasing thesupply of fuel in accordance with temperature variations in saidrefrigerant evaporating means independently of the temperature in thespace being cooled and of the ambient temperature, and valve meansresponsive to the temperature in said refrigerant generating means forcontrolling the so-regulated supply of fuel to said burner means.

24. In refrigerating apparatus of the intermittent absorption typeincluding refrigerant evaporating means and at least two units operatingin phase relation to each other, to flow esteem liquid refrigerantsubstantially continuously to said refrigerant evaporating means for theproduction of substantially continuous refrigeration to cool an enclosedspace, each unit having a boiler-absorber and a fuel burner therefor; aunitary thermostat control including a valve responsive to thetemperature in the space being cooled for increasing and decreasing thesupply of fuel in accordance with temperature variations in the saidspace, a second valve responsive to the temperature outside the spacebeing cooled for varying the maximum amount of fuel regulated by saidfirst named valve relative to the ambient temperature, a third valveresponsive to the temperature of said refrigerant evaporating means forincreasing and decreasing the supply of fuel in accordance withtemperature variations in said refrigerant evaporating meansindependently of the temperature in the space being cooled and of theambient temperature, and valve means responsive to the temperature ineach of said boiler-absorbers for selectively controlling theso-regulated supply of fuel to said fuel burners.

NILS ERLAND AF KLEEN.

